This application claims the priority of German patent document 198 06 150.1, filed Feb. 14, 1998, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a vehicle with a device for detecting objects in an area having a specified horizontal extent, by means of radiation-based scanning of the area and an obstacle evaluation unit.
Various kinds of such vehicles are known, in which the object detection device can be used to detect other vehicles in the so-called blind spot (the side area behind the vehicle which is difficult for the driver to see, especially the left rear side area), or to detect the pattern of road markings, standing objects (especially other vehicles) and parking spaces between standing objects, and to determine their size, or for another, similar purpose. Optical systems, such as infrared scanning systems or video cameras as well as acoustic systems, such as sound and radar systems are used for zero-contact radiation-based scanning of an area under observation. Object detection devices as aids for parking are described for example in German patent documents DE-OS 37 28 948 A1 and DE 38 13 083 C3. German patent document DE 195 07 957 C1 discloses a vehicle with a laterally mounted optical scanning device in the form of an infrared scanning system that serves to detect lane boundaries. Additional optical scanning devices are optionally provided on the other sides of the vehicle to provide bilateral or omnilateral monitoring of the surroundings to detect objects which may be located therein.
One object of the present invention is to provide a vehicle of the type described above at the outset in which the area under observation can be monitored reliably at relatively low expense for objects that might appear.
Another object of the invention is to provide such a system which can distinguish between detected objects with regard to their direction of motion relative to the direction of motion of the vehicle. The object detection device thus employed can be used flexibly for other applications if necessary.
These and other objects and advantages are achieved by the object detection device according to the invention, in which an evaluation unit evaluates the scanning information from two or more strip-shaped portions of the area under observation that have horizontal components which are differently inclined relative to the lengthwise direction of the vehicle, or are offset in the lengthwise direction of the vehicle with time resolution. When an object appears, the unit distinguishes between objects that are moving in the direction of travel of the vehicle and objects that are at rest or oncoming, based on the sequence of responses from the portions under observation. Any conventional scanning system based on electromagnetic radiation or acoustic waves can be used as the scanning means in the object detection device. In particular, infrared, radar, and ultrasound systems can be used, with individual direction-specific scanning elements which cover individual portions of the area under observation, as well as video camera systems in which the strip-shaped portion under observation corresponds to matching image portions of the video image recorded from the area under observation.
In this manner, objects that appear in the area under observation can be detected reliably at relatively low expense. It is also possible to distinguish between objects that are at rest or oncoming and objects that are moving in the direction of travel of the vehicle. In particular, overtaking vehicles that enter the area under observation can be distinguished from stationary objects outside the lane and from oncoming vehicles. The separate time-resolution evaluation of various portions of the area under observation also provides the necessary conditions for flexible application of the object detection device to other purposes, such as finding parking spaces and special detection of vehicles changing from behind the vehicle to a passing lane.
In one embodiment of the invention, the object detection device is designed so that it can be used advantageously for detecting and measuring parking spaces. For this purpose, when the vehicle speed is below a presettable threshold value, the object detection device is automatically switched to the corresponding parking space detection mode. An associated flasher signal is switched on. In this particular mode, the portion under observation with horizontal components that are essentially parallel to the transverse direction of the vehicle is scanned. Moreover, the area under observation is preferably not scanned in this operating mode, keeping energy consumption and data processing cost low. The scanning information from this scanning strip, which extends in a horizontal plane essentially perpendicularly to the travel direction, can be used to detect parking spaces between standing vehicles which the vehicle passes and to determine the size of such parking spaces, for which purpose the evaluation unit evaluates this scanning information appropriately.
In another embodiment of the invention, the object detection device is designed so that overtaking vehicles entering the area under observation can be distinguished depending on whether they have already been in the passing lane for a long period of time or whether they have just pulled out into the passing lane from behind the vehicle, especially from its wake. The latter situation represents an increased danger potential which can be specifically detected with this embodiment. For this purpose, the portions under observation have a limited range between approximately 3 meters and 20 meters, preferably approximately 5 meters, and have a pattern with horizontal components that extends fanwise from the vehicle in such fashion that at least one strip-shaped portion with predominantly rearward components extends laterally over the vehicle for less than the vehicle width.
With this improvement, reliable recognition of an increased danger situation can be provided in which a following vehicle suddenly pulls out from behind the vehicle itself, i.e. from its wake. In this case, initially the scans associated with the portion that faces primarily rearward respond before the scans of the portions extending further laterally respond successively. These scans respond in succession according to the fanwise structure of the portion of the area under observation. On the other hand, the portion facing primarily rearward does not respond to a vehicle approaching from farther back in the passing lane, since it extends only slightly laterally over the vehicle itself and not mainly into the area of the passing lane, so that these two passing situations can be distinguished reliably.